The first set of scales shows the mass of an empty bowl. The second set of scales shows the mass of the bowl containing some sugar. Calculate the mass of sugar in grams.

Step 1 ：Let the weight of the empty bowl be \(b\) grams and the weight of the sugar be \(s\) grams.

Step 2 ：The first set of scales gives us the equation \(b = x\), where \(x\) is the reading on the first set of scales.

Step 3 ：The second set of scales gives us the equation \(b + s = y\), where \(y\) is the reading on the second set of scales.

Step 4 ：We are looking for the value of \(s\), which is equal to \(y - x\).

Step 5 ：Subtract the first equation from the second to get \(s = y - x\).

Step 6 ：Substitute the values of \(x\) and \(y\) from the scales into the equation to get the weight of the sugar.

Step 7 ：Therefore, the weight of the sugar is \(\boxed{y - x}\) grams.